Storage or warehouse systems may include multi-level storage racks for storing loads, such as boxes, containers or pallets, at each of the multiple levels. Access to the stored loads may be provided by a shuttle system including multiple remotely controlled robotic devices or shuttles arranged on each level. The shuttles move back and forth in a single horizontal direction within one storage level to access stored goods arranged on the corresponding level and carry them.
A lifting mechanism, such as a forklift, is provided to move loads in a vertical direction from the ground to the respective level of the storage rack or from the respective level to the ground. The forklift lifts newly arriving goods to the respective level and loads them to the shuttles that deliver the goods to required storage cells at that level. Similarly, shuttles retrieve goods from the storage cells and deliver them to the forklift raised to the respective level. The forklift unloads the goods from the shuttles and moves them in a vertical direction down to the ground.
However, the number of lifts in any efficient storage system employing multiple shuttles is substantially less than the number of shuttles. Therefore, “bottlenecks” are created near the lifts, reducing the throughput of the storage system.
Therefore, there is a need for a new “self-lifting” technique that would enable a robotic device, such as a shuttle, to move in a vertical direction without assistance of an external lift.
My copending U.S. patent application Ser. No. 13/675,433 filed on Nov. 13, 2012, entitled SELF-LIFTING ROBOTIC DEVICE WITH LOAD HANDLING MECHANISM and incorporated herewith by reference, discloses a robotic device that carries multiple boxes held in multiple rows. However, this robotic device is not able to move in a vertical direction when it carries the maximum number of boxes that can be loaded onto the robotic device.
Hence, there is a need for a robotic device capable of moving in a vertical direction while carrying the maximum possible load.